This invention relates to a robot and particularly to a so-called five-axis robot for controlling the position of a device which performs an operation on a workpiece. Examples of such operations are blasting (both dry and wet), plasma coating and the like. This invention more particularly relates to a five-axis robot for positioning a device for performing an operation on workpieces located within a relatively large enclosure.
Robots have been designed for positioning certain operative devices that perform operations on workpieces by moving such devices along many different axes both rectilinear and rotational for specific uses in specific environments. For example, U.S. Pat. No. 3,665,148 entitled SIX-AXIS MANIPULATOR discloses a machine which includes a six-axis manipulator for positioning a work head such as a spot welder which moves to different positions with respect to articles moving past the machine. Such type of robots have gained acceptance as highly efficient apparatus for performing work processing operations. However, each operation presents certain problems requiring the design of mechanisms unique to the requirements of the operation.
The design of manipulators or robots for such unique operations requires substantial new concepts and development of the same so that the positioning of orientation of the device for performing operations on the workpieces is accurately controlled. Conventionally, the positioning of the operative devices is controlled by a digital control program including a memory unit which serves to sequentially move the device through predetermined patterns of motion.
The various motions to the specific positions of operative devices are generally known as motions along either rectilinear axes or rotational axes. For example, U.S. Pat. No. 3,665,148 discloses a six-axis robot having guided movement along three rectilinear axes and three rotational axes. It, however, has complicated, expensive, cumbersome structure that would be extremely difficult if not impossible to use in overhead type of suspended robots.
Another type of robot is disclosed in U.S. Pat. No. 4,882,881 entitled ROBOT POSITIONER AND SEAL ARRANGEMENT FOR AN ENCLOSED CHAMBER which is a four-axis robot that moves and positions a blasting gun within an enclosure. Such robot moves the gun along rectilinear axes extending rearwardly and laterally across the room and also up and down at various heights. It also rotates the blasting gun to various angles around a rotatable axis.